Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.
Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) claims almost 2 million lives annually ((Dye, 2010) and globally is the leading cause of death due to a single bacterial agent. The situation has become more critical in the past decade due to co-infection with HIV and the inefficiency of the current vaccine, Bacillus Calmette-Guérin (BCG), to protect adults against TB ((Dye, 2010).
The identification of novel and protective antigens recognised by infected individuals would represent a major advance in the control of TB and may form the basis of new therapeutics to limit disease spread.
Current TB vaccines in clinical trials include viral-vectored or adjuvant-based subunit vaccines, as well as whole mycobacterial vaccines, that express one or more immunogenic M. tuberculosis antigens ((Kaufmann, 2011). Most of these strategies are based on secreted antigens of M. tuberculosis that are presumably more readily ‘seen’ by the host immune response (reviewed in ((Kaufmann, 2011)). The protective efficacy in humans of these new candidate vaccines yet to be determined.
There remains a need for further candidate antigens and vaccines for prevention and/or treatment of Mycobacterium infection, especially M. tuberculosis infection.
Further to identification of antigens, the targeted modulation of antigen expression in antigen presenting cells by recombinant vaccine vehicles such as Bacille Calmette Guerin (BCG) would significantly aid development of effective immunotherapeutic strategies.
There remains a need for candidate expression systems, especially those capable of an immediate and sustained expression of protective antigen, thereby enabling improved antigen specific immune responses to Mycobacterium, especially M. tuberculosis. 